The present invention relates to a key device and a method for assembling the same.
Some of conventional key devices have a key case with 2-piece configuration. Such key case contains an electronic part, for example, a wireless module such as a transmitter device for keyless entry.
As shown in FIGS. 3(A) and (B), a 2-piece key case 61 comprises a first case piece 62 and a second case piece 63. A wireless module (not shown) is contained in a space defined by the first case piece 62 and the second case piece 63. A key plate 64 is integrated to the first case piece 62 by insert molding. A female screw is formed in the center body adjacent to the proximal portion of the key plate 64. The second case piece 63 has a hole corresponding to the female screw. Thus, the second case piece 63 is fixed to the first case piece 62 by screwing a screw 65 with the female screw through the hole.
Recently, key cases are desired to have better design appearance as the external appearance of car accessories have been improved. For example, a key case with 3-piece configuration, in which a thick center body is arranged between the first case piece and the second case piece to provide a stately appearance is desired.
In such a 3-piece key case, when a key plate is integrated to the center body by the insert molding, these three parts cannot be integrally secured by a single screw as conventional. For example, the first case piece can be fixed to the center body by a screw. However, it is undesirable to use a long screw for the key case with considering the strength of the screw. When the first case piece and the center body are fitted by a screw, such assembly become thicker. Accordingly, it is impossible to further secure the second case to the assembly by the same single screw which has a normal length.
In such case, the second case may be secured, for example, by adhering, fitting with another screw, or ultrasonic wave welding.
However, adhering requires a long dry time and a place for keeping the key device until the adhesives are dried. Thus, the assembling of the key device becomes troublesome.
If the second case piece is fixed to the center body by another screw, two screws are needed totally. Then the number of parts is increased, causing the manufacturing cost to be raised.
Furthermore, the ultrasonic wave welding is not suitable for the manufacturing of the key device because of the following reasons. When another electronic part such as a transponder is contained in a space defined by the center body and the second case piece, and then the second case piece is fitted to the center body, the ultrasonic wave may adversely affect the electronic part.
For example, Japanese Laid-Open Patent Publication No. 7-238721 discloses a key device having a cavity to contain electronic parts in a case. The above described key device is configured so that the cavity containing the electronic parts can be closed by a cover. The cover has a plurality of claws. By engaging these claws with engaged potions in the case part, the cover can be fitted to the case. However, in this key device, once the cover is attached to the case, the claws cannot be manipulated to release the claws from the engaged portion, and the cover thus cannot be removed. This makes the maintenance of the electronic parts contained in the case impossible. If a battery is included in the electronic parts, the battery also cannot be exchanged.